In optical fiber communications, an optical fiber sometimes has to be analyzed to determine if a disconnect in the optical pathway exists and/or where the disconnect is located. For example, in some instances, it may be that the location of a fault within an optical fiber has to be ascertained, so that the disconnect can be repaired.
Oftentimes, this is accomplished by disconnecting the optical fiber from a transmitter and/or receiver so that the optical pathway of the optical fiber can be tested. The testing typically involves attaching an end of the optical fiber to a separate testing apparatus.
Optical Time-Domain Reflectometry (OTDR) is one method used to locate such faults (e.g., disconnect in the fiber) in fiber optic networks. In this method, a laser pulse is sent down a test fiber and reflected back by a fault in the optical pathway. The reflected laser pulse is then received by a photodetector. The time period elapsed since the signal was sent indicates how far down the pathway the fault is located.
However, the use of a separate testing apparatus to locate faults within an optical fiber can be time consuming and costly. In order to test the optical pathway, the testing equipment can be connected via a fiber access point which adds components to the optical network and can degrade the signal as it travels along the optical pathway.
Alternatively, an end of the optical fiber can be located and disconnected from the optical network. For example, optical pathways forming an optical network are typically constructed using a number of optical fibers. Each optical fiber section is attached to the end of another optical fiber section. In some embodiments, an end of one of the optical sections can be accessed and the testing equipment can be connected thereto. Such methods also result in periods where the fiber is out of the communications network and therefore can result in network downtime.
Furthermore, in some instances, a trained operator may have to be present to use the specialized testing apparatus. The separate test apparatus that has been proposed for use in diagnosing such disconnects includes a separate laser and photodetector that is to be connected to an optical fiber via a splitter. The splitter is used so that an outgoing light pulse is routed from the laser to the optical pathway, while a reflected signal is directed to the detector rather than back to the laser.